1. Field of the Invention
The present invention relates to a holder, a lithography apparatus, and a method of manufacturing an article.
2. Description of the Related Art
Along with the advance of semiconductor devices toward higher density and micronization degree, exposure apparatuses used to manufacture them have raised the numerical aperture (NA) of the projection optical system. As the NA of the projection optical system rises, the resolving power of the exposure apparatus improves, but the effective depth of focus decreases. Hence, an exposure apparatus is required to hold a substrate with a high degree of flatness, and Japanese Patent Laid-Open No. 2004-140071 proposes a related technique.
In addition, to attain high productivity, the throughput of the exposure apparatus is enhanced and, for example, there is a need for a stage for holding a substrate which increases the acceleration. One method of implementing the high acceleration of the stage is to reduce the weight of the stage, and attempt to reduce the weight of a holder (chuck) that chucks and holds a substrate have been made.
However, as the holder is made thinner to reduce the weight of the stage, the rigidity of the holder itself lowers. Hence, flexture of the holder itself affects the plane correction performance of the substrate.